This proposal presents a broad program whose goal is to provide key pieces of basic information required to better understand the etiology and pathogenesis of dental caries and various forms of periodontal disease, and to formulate rational approaches for their control. The program integrates the efforts of investigators experienced in the areas of microbiology, animal experimentation, electron microscopy, nutrition, periodontology and clinical dentistry, and represents an extension of on-going studies. The specific aims include attempts to develop and refine methodology for studying important oral bacteria, and studies of the properties of odontopathic bacteria which account for, or influence their virulence. Other aims relate to elucidating parameters which influence the transmission and acquisition of prominent oral bacteria. Special emphasis is being devoted to studies of host and environmental factors which affect the colonization of potentially- important odontopathic bacteria. Included are studies of the influence of dietary components, topically-applied fluorides, polymorphonuclear leucocytes and their products, certain antibodies, intraoral location, and fibronectin on oral microbial colonization.